Infrared-transparent glass ceramics: An exploratory study.

In this work, the vision and need for a fully ceramized long-wave infrared (LWIR)-transmitting glass ceramic have been articulated. Three sulfide systems were explored including two with La 2 S 3 in hopes of imparting strong bonds from this refractory sulfide, and two containing GeS 2 in hopes of widening the glass-forming region. Attempts were made to produce glasses in the Ga 2 S 3 –La 2 S 3 –(ZnS,CaS) system, the GeS 2 –La 2 S 3 system, and the GeS 2 –Ga 2 S 3 –CdS system. Water quenching produced glasses of Ga 2 S 3 –La 2 S 3 –CaS and GeS 2 –Ga 2 S 3 –CdS. Microstructural and thermal analyses were used to explore nucleation and growth in these systems and infrared transmission and mechanical hardness showed potential for LWIR window use. The GeS 2 –Ga 2 S 3 –CdS system showed good LWIR transmission and pre-crystallized hardness superior to chemical vapor deposited ZnS. The Ga 2 S 3 –La 2 S 3 glasses did not appear to be viable candidates at this time due to a small temperature window between crystallization and glass transition temperatures and problems with oxygen contamination in the La 2 S 3 source. Suggestions are made for two alternative methods for producing fully ceramized LWIR-transmitting glass ceramics. [ABSTRACT FROM AUTHOR]